I am knitting a Patons Shetland Chunky pattern, 15 sts= 4 ins with size 10 needles with a Reynolds Lopi yarn, 14 sts= 4 ins with size 10 needles. Will this substitution work? I'm having a hard time getting the proper gauge. I'm down to size 6 needles and getting 13 sts= 4 ins. I must be doing something wrong, improperly measuring the stitches in my swatch or something. The store I bought the yarn from said this substitution would work. Any suggestions will be appreciated.

The swatch I knitted was 22 stitches. I took the swatch into the yarn shop where I bought the yarn and the sales clerk thought it was ok to keep reducing needle size. I just don't think it's right to reduce that many sizes. I'll do another swatch with more stitches on the needle to see what results I get.